While technology continues to make rapid advancements in the medical field, there are still a number of diseases and ailments that strike a vast number of adults and can lead to death. For example, a stroke is currently the third leading cause of death in American and is also unfortunately a leading cause of adult disability. A stroke, which also referred to as a “brain attack,” occurs when a blood clot blocks an artery (a blood vessel that carries blood from the heart to the body) or a blood vessel (a conduit through which blood moves throughout the body) ruptures and thereby interrupts blood flow an area of the brain. When either of these events occurs, brain cells begin to die and brain damage occurs.
As a result of the interruption in blood flow and brain cells dying during a stroke, the affected area of the brain is unable to function and abilities controlled by that area of the brain are lost. These abilities include but are not limited to movement (ability to move one or more limbs on one side of the body), speech (ability to understand or formulate speech), memory, and sight (ability to see one side of the visual field). How a stroke patient is affected depends on where the stroke occurs in the brain and how much of the brain is damaged. For example, an individual who has a small stroke may experience only minor problems such as weakness of an arm or leg. Individuals who have larger strokes may be paralyzed on one side or lose their ability to speak. Some people recover completely from strokes, but more than ⅔ of survivors will have some type of disability for the rest of their lives. More specifically, many survivors suffer from residual neurological deficits that persistently impair function. In particular, dysfunction from upper extremity (UE) hemiparesis impairs performance of many daily activities such as dressing, bathing, self-care, and writing and as a result, functional independence is greatly reduced. In fact, studies show that only 5% of adults regain full arm function after stroke and unfortunately, 20% regain no functional use.
For a person that survives a stroke, the person will most likely undergo stroke rehabilitation which is the process by which patients with disabling strokes undergo treatment to help the patients return to a normal life as much as possible by regaining and relearning the skills of everyday living. This can be a very long and difficult process and therefore is very challenging and difficult for the patient and all loved ones. As a result, stroke rehabilitation also aims to help the survivor understand and adapt to the difficulties ahead, prevent secondary complications and educate family members to play a supporting role and assist the survivor as much as possible and where needed.
Depending upon the severity of the stroke, the rehabilitation program will vary and thus the makeup of the rehabilitation team will also vary. In any event, a rehabilitation team is usually multidisciplinary since it involves staff with different skills that are all working together to help the patient recover and relearn and develop old skills and abilities. The rehabilitation staff can include but is not limited to nursing staff, physiotherapy, occupational therapy, speech and language therapy, and usually a physician trained in rehabilitation medicine. Other rehabilitation programs will include assist from psychologists, social workers, and pharmacists since unfortunately, a large number of patients manifest post-stroke depression, and other social problems related to their disability. However, most stroke patients undergo physical therapy (PT) and occupational therapy (OT) and therefore, these are considered cornerstones of the rehabilitation process. During the rehabilitative process, assistive technology, such as a wheelchair, walkers, canes and orthosis are commonly used to assist the patient and to compensate for impairments. Speech and language therapy is provided for patients with problems understanding speech or written words, problems forming speech and problems with swallowing. While PT and OT have overlapping areas of working, their main attention fields are different in that PT involves re-learning functions such as transferring, walking and other gross motor functions. In contrast, OT focuses on exercises and training to help relearn everyday activities known as the activities of daily independent living, such as eating, drinking, dressing, bathing, cooking, reading and writing, and toileting, etc.
It is generally accepted in the medical community that there is an important treatment window for beginning the rehabilitative process. Traditionally, methods of stroke rehabilitation have been focused on the first three months after stroke and consist largely of passive (nonspecific) movement approaches or compensatory training of the nonparetic arm. This time window is in part based on and consistent with natural history studies of stroke recovery that show a plateau after three months, although it has been demonstrated that recovery can occur well beyond this window into the late chronic phase several years post-stroke. Features of the motor impairment are however different in the period immediately after stroke (i.e. the first 3 months or so) and in the later post-stroke period (after 3 months). In the beginning there is predominantly weakness, but later muscular overactivity develops in certain muscle groups that leads to abnormal posturing and masks strength gains in the non-overactive muscle groups.
Much of the therapy provided by PTs and OTs in the first 3 months is hands-on, and is spent in passively maintaining range-of-motion in the joints of the affected side so as to prevent deformity and in teaching compensatory strategies to preserve functional independence to the extent possible using the unaffected limb, assistive devices and the like. Little time and effort is expended in trying to restore muscle activation/strength in the paralyzed affected limb. With respect to rehabilitative treatment for people suffering with chronic hemiparetic arm dysfunction, there are a number of new devices for upper arm rehabilitation and training. Most of these devices concentrate on the affected arm and use mechanical devices/robotics and electrical stimulation to controllably move the affected arm. For example, there are robotic devices that facilitate movement of the targeted muscle group or groups by using a robot to sense and then stimulate appropriately if the patient is not able to complete the intended movement. These new rehabilitation devices were introduced to allow increased amounts of ‘practice’ to train the affected limb while reducing the burden on the therapist. However, these devices are overly complex, expensive (since they use computers (virtuals) and robotics), and “train” the affected limb by producing passive movements in one or more joints using an external source of energy. The complexity and costs of these devices prevent them from being used in a number of settings, including a home or remote clinic that does not have sufficient resources for purchase of expensive equipment, etc.
A number of recent studies have shown that recovery is an “active” rather than a “passive” process where it is the brain that needs to be trained in conjunction with movements of the limb. Over the last few decades it has been shown that there is a complex interaction between the two sides of the brain in the control of movement of one limb. Both sides of the brain contribute to the control of each limb, but one side is usually “inhibited” in a healthy individual. However this inhibition is removed when one side is damaged, and as a result the undamaged side of the brain may play a greater role in the recovery of the affected limb. Existing rehabilitation devices are not focused on harnessing the already available brain activity from the unaffected side to train affected arm movements.